Jos: Two bombs blamed on the Islamic extremist group Boko Haram exploded at a crowded mosque and a posh Muslim restaurant in Nigeria's central city of Jos, killing 51 people, officials said on Monday.

The blasts last night came hours after a woman suicide bomber blew up at a crowded evangelical Christian church service in the northeastern city of Potiskum, killing six people, according to witnesses.

Also yesterday, extremists returned to northeastern villages attacked three days earlier, killing nine villagers and burning down 32 churches and about 300 homes, said Stephen Apagu, chairman of a self-defense group in Borno state's Askira-Uba local government area. He said the militia killed three militants.

Yesterday's attacks are the latest in a string blamed on Boko Haram that have now killed about 300 people in the past week. In the most deadly, more than 140 people were killed, most men and boys as they prayed in mosques in northeastern Kukawa town on Wednesday.

The attacks may correspond to an Islamic State group order for more mayhem during the Muslim holy month of Ramadan. Boko Haram became the Islamic State group's West Africa franchise earlier this year.

In Jos, 51 people died and were buried this morning, Muslim community lawyer Ahmed Garba told a news conference.

Another 67 people were wounded, according to Abdussalam Mohammed, the National Emergency Management Agency coordinator. Police confirmed the explosions but said a final toll must wait as they are still excavating rubble.

The explosion at the Yantaya Mosque came as leading cleric Sani Yahaya of the Jama'atu Izalatul Bidia organization, which preaches peaceful co-existence of all religions, was addressing a crowd, according to survivors.

Gunmen opened fire on the mosque from three directions, said Garba, the lawyer.

Survivor Danladi Sani said he saw a man robed in white open fire aimed at Yahaya, and then blow himself up. Yahaya was unharmed, he said.

Another bomb exploded at Shagalinku, a restaurant patronized by state governors and other elite politicians seeking specialties from Nigeria's mainly Muslim north, witnesses said.

Sabi'u Bako bought a take-out and then heard a massive blast as he walked away with friends. "The restaurant was destroyed and we saw many people covered in blood," he said. "We can't believe that we escaped."

Jos is a hotspot for violent religious confrontations, located in the center of the country where Nigeria's majority Muslim north and mainly Christian south collide. The city has been targeted in the past by bomb blasts claimed by Boko Haram extremists that have killed hundreds of people.